renal sac的用法和样例：
例句
- Here is a much larger simple renal cyst of the upper pole.
肾脏上极更大的单纯性肾囊肿，还有一些小囊肿散布于肾脏。 - Conclusions Typical cystic renal carcinomas can be well diagnosed, while atypical cases may be misdiagnosed in benign renal cysts by ultrasonography.
结论超声能对典型囊性肾癌作出正确诊断，但不典型者可误诊为良性肾囊肿。
